I have a KVM guest that I would like to dynamically change the memory allocation of.
At the moment, to change the memory of the guest, I have to run:
sudo virsh edit $GUEST_DOMAIN
Then change the first line shown in the following section from the config
...
<memory unit='KiB'>512000</memory>
<currentMemory unit='KiB'>512000</currentMemory>
<memtune>
<hard_limit unit='KiB'>256000</hard_limit>
</memtune>
...
and then restart the guest with virsh shutdown
and virsh start
.
I have been trying to use virsh memtune --hard-limit 512000 --domain $GUEST_ID
(reference) but it appears to have no effect.
I also tried "ballooning" from inside the guest using the docs here, but I keep getting the error
balloon: command not found
Question
Is there a way to dynamically resize the KVM guest with a command from the host. If not, is there at least a way to resize the memory with a command, and not have to edit a config file (or pershaps the virsh file can be edited with sed)?
Extra Info
The guest is using a qcow2 sparse file.
Below is the full config from sudo virsh edit $GUEST
<domain type='kvm'>
<name>svn.mydomain.com</name>
<uuid>8463ab11-628a-c07c-4366-4f768247934a</uuid>
<memory unit='KiB'>512000</memory>
<currentMemory unit='KiB'>512000</currentMemory>
<memtune>
<hard_limit unit='KiB'>256000</hard_limit>
</memtune>
<vcpu placement='static'>4</vcpu>
<os>
<type arch='x86_64' machine='pc-i440fx-trusty'>hvm</type>
<boot dev='hd'/>
</os>
<features>
<acpi/>
<apic/>
<pae/>
</features>
<clock offset='utc'/>
<on_poweroff>destroy</on_poweroff>
<on_reboot>restart</on_reboot>
<on_crash>restart</on_crash>
<devices>
<emulator>/usr/bin/kvm-spice</emulator>
<disk type='file' device='disk'>
<driver name='qemu' type='raw'/>
<source file='/media/storage/kvm/vms/svn.mydomain.com.img'/>
<target dev='vda' bus='virtio'/>
<address type='pci' domain='0x0000' bus='0x00' slot='0x03' function='0x0'/>
</disk>
<disk type='block' device='cdrom'>
<driver name='qemu' type='raw'/>
<target dev='hdc' bus='ide'/>
<readonly/>
<address type='drive' controller='0' bus='1' target='0' unit='0'/>
</disk>
<controller type='usb' index='0'>
<address type='pci' domain='0x0000' bus='0x00' slot='0x01' function='0x2'/>
</controller>
<controller type='pci' index='0' model='pci-root'/>
<controller type='ide' index='0'>
<address type='pci' domain='0x0000' bus='0x00' slot='0x01' function='0x1'/>
</controller>
<interface type='bridge'>
<mac address='52:54:00:a2:4a:f6'/>
<source bridge='kvmbr0'/>
<model type='virtio'/>
<address type='pci' domain='0x0000' bus='0x00' slot='0x02' function='0x0'/>
</interface>
<serial type='pty'>
<target port='0'/>
</serial>
<console type='pty'>
<target type='serial' port='0'/>
</console>
<memballoon model='virtio'>
<address type='pci' domain='0x0000' bus='0x00' slot='0x04' function='0x0'/>
</memballoon>
</devices>
</domain>
You don't need to be messing with
<memtune><hard_limit>
. This is actually a rather dangerous setting when applied to KVM guests. I would remove that section immediately.To reduce the amount of memory the KVM guest has access to right now, change
<currentMemory>
. The maximum the guest can have is specified by<memory>
, and changing it requires shutting down the guest.